The invention relates to the field of interconnects or electrodes for integrated MEMS devices.
Integrated microelectromechanical systems (MEMS) devices are monolithic (single-chip) MEMS devices that contain electrodes with sensing, control or processing circuitry. The production of integrated MEMS devices is based, in large part, upon well-developed techniques in the disciplines of integrated circuit semiconductor manufacturing and photolithography. As such, these devices use metal interconnects/electrodes similar to those for traditional integrated devices. Optical MEMS (such as a micro-mirror for fiber-optic switching), however, require metal interconnects that provide a noble metal surface in the bond pads for epoxy bond. In addition, stress requirements for optical MEMS preclude the use of passivation films over the interconnects. Therefore, the metal of the interconnect must be inert. Similarly, Bio-MEMS devices (such as a DNA analysis chip) require electrodes that are corrosion resistant in the context of exposure to biological substances. These requirements are not met by traditional interconnects/electrodes, such as copper or aluminum interconnects/electrodes produced in standard integrated circuit (IC) processing facilities.
Therefore, the present invention provides a metallization stack utilizing platinum as a noble metal for use in integrated MEMS devices, particularly optical MEMS and Bio-MEMS devices. The present invention also provides a method of patterning platinum.